Is Alberta Flooding a Sign of Climate Change?

It seems hardly a week goes by when we don't hear some climatologist or other expert say, "it's difficult to connect one particular weather event to global warming, but..." We heard it this week as communities in Calgary and Southern Alberta were evacuated in the face of extreme rainfall and rising floodwaters.

The "but," of course, is that we know burning fossil fuels and pumping carbon dioxide and other heat-trapping greenhouse gases into the atmosphere causes the Earth's average surface temperatures to rise. That warming leads to climate change, which generates increased extreme weather-related events. Those events, according to the World Meteorological Organisation's "Statement on the Status of the Global Climate in 2012," include "major heatwaves and extreme high temperatures, drought and wildfires, extreme precipitation and floods, snow and extreme cold, and tropical cyclones."

As the report points out, "Natural climate variability has always resulted in such extremes, but the physical characteristics of extreme weather and climate events are being increasingly shaped by climate change."

In many ways, climate change is about water change. For every one degree increase in temperature, the atmosphere's ability to hold water increases seven per cent. Massive amounts of water from melting ice sheets are being liberated while evaporation increases from oceans that cover 70 per cent of Earth's surface. Meanwhile greater turbulence and instability of the atmosphere and jet stream dump heavier loads of water and increase the frequency of extreme events like tornadoes and hurricanes.

Despite what we know about climate change, and despite the fact that less than one per cent of climate scientists dispute the prevailing research behind human-caused warming, we still see news outlets, industry and others trying to convince us that it's not happening or that it's not a big deal. And we see governments refusing to act in any meaningful way.

As I wrote in a recent column, "When people around the world apply rigorous scientific method to study our actions and their impacts on the things that keep us alive and healthy -- clean air, water, soil and biodiverse plants and animals -- we must listen, not just about climate, but about a range of issues."

Air, water and land are intimately and complexly interconnected in ways that we still barely comprehend. For years, the insurance industry has warned us that exploding costs of climate-related claims must be met with greenhouse gas emissions reductions. In light of that, it's shocking, after so many years of denial that human-induced climate change is real, to hear some pundits now calling for adaptation rather than demanding a massive program to slow climate change.

Can we say the recent flooding and extreme weather in Southern Alberta and B.C. were caused by global warming? Maybe not, but we can say we should expect more of the same - and worse if we don't do something to get our emissions under control. As many scientists warn, climate change isn't coming; it's here. We may be able to adapt to and cope with some of its current effects, but it will become increasingly difficult if we continue to ignore the need to wean ourselves off fossil fuels, through conservation and switching to cleaner energy.